-> “WhatsApp Messenger is a cross-platform mobile messenger that replaces SMS and works through the existing internet data plan of your device. WhatsApp is available for iPhone, BlackBerry, Android, Windows Phone, Nokia Symbian60 & S40 phones. Because WhatsApp Messenger uses the same internet data plan that you use for email and web browsing, there is no cost to message and stay in touch with your friends.”

+> “WhatsApp Messenger is a cross-platform mobile messenger that replaces SMS and works through the existing internet data plan of your device. WhatsApp is available for iPhone, BlackBerry, Android, Windows Phone, Nokia Symbian60 & S40 phones. Because WhatsApp Messenger uses the same internet data plan that you use for email and web browsing, there is no cost to message and stay in touch with your friends.”

WhatsApp uses some sort of customized XMPP server, named internally as FunXMPP, which is basically some extended proprietary version.

### Login procedure

-Much like XMPP, WhatsApp uses JID (jabber id) and password to successfully login to the service. The password is hashed and happened to be an MD5’d, reversed-version of the mobile’s IMEI (International Mobile Equipment Identity) or equivalent unique ID, stored in servers upon account creation and used transparently everytime the client connects the server.

+Much like XMPP, WhatsApp uses JID (jabber id) and password to successfully login to the service. The password is hashed and happened to be an MD5’d, reversed-version of the mobile’s IMEI (International Mobile Equipment Identity) or equivalent unique ID, stored in servers upon account creation and used transparently everytime the client connects the server.

-The JID is a concatenation between your country’s code and mobile number.

+The JID is a concatenation between your country’s code and mobile number.

Initial login uses Digest Access Authentication.

### Message sending

-Messages are basically sent as TCP packets, following WhatsApp’s own format (unlike what’s defined in XMPP RFCs).

+Messages are basically sent as TCP packets, following WhatsApp’s own format (unlike what’s defined in XMPP RFCs).

Despite the usage of SSL-like communication, messages are being sent in plain-text format.